Methods of treating keratin hyperproliferation disorders using mTOR inhibitors

ABSTRACT

A method of treating or preventing keratin hyperproliferation skin disorders is set forth. The method includes the administration of an mTOR inhibitor to a subject afflicted with the hyperproliferation disorder. The mTOR inhibitor can be administered to the subject via any means known in the art including oral, topical, and transdermal administration.

PRIORITY INFORMATION

This application is a continuation of U.S. patent application Ser. No.11/985,850, filed Nov. 16, 2007, now issued as U.S. Pat. No. 9,205,080,which claims the benefit of U.S. Provisional Application No. 60/866,161,filed Nov. 16, 2006, each of which are herein incorporated by reference.

BACKGROUND

Keratin hyperproliferation disorders afflict a large number ofindividuals. Most of these disorders have no cure and the treatmentsprimarily focus on amelioration of the symptoms of the disorders. Assuch research continues to discover methods of treatment for thesediseases.

SUMMARY

The present invention is drawn to a method of treating or preventingkeratin hyperproliferation skin disorders in a subject. The methodincludes administering to the subject a therapeutically effective amountof an mTOR inhibitor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an overview of mTOR signaling in mammals mammals (figuremodified from K. Yonezawa, Mol Interv., 2003). The mammalian target ofrapamycin (mTOR) is a key modulator of signal transduction leading toefficient translation of certain classes of messenger RNAs includingthose that contain a terminal oligopyrimidine (TOP) regulatory motif. Inthe proposed model, rapamycin blocks signal transduction by binding tomTOR resulting in decreased translation of TOP mRNAs (including K6aaccording to the model proposed here) at the level of ribosomeinitiation, resulting in decreased K6a protein synthesis.

FIG. 2 shows a comparison of the sequences of the 5′ untranslatedregions (UTRs) of the common keratins including the inducible keratinsK6a, K6b, K16 and K17. The location and presence of terminaloligopyrimidine (TOP) elements in the inducible keratins are shown inyellow. The lack of a TOP element does not mean it does not exist butrather may reflect the lack of proper identification of the 5′ end ofthe messenger RNA. For example, immediately upstream of the human K6b 5′terminal “c” residue is the sequence cttctcctccctctg (see NCBI accession#L42584), suggesting it is also a TOP mRNA and the sequence listed maynot contain the full-length 5′ UTR. It should be noted that theregulatory pyrimidine element need not be at the terminus of the 5′UTRin order to be functional (see Kasper et al., J. Biol. Chemistry, 1992).

FIGS. 3A-3B show results of rapamycin treatment of human keratinocytes.FIG. 3A Panel 1 shows results by western blot analysis of the effect onK6 expression in human keratinocyte cells when treated with increasingconcentrations of rapamycin and harvested. FIG. 3A Panel 2 showsquantitated values (from Panel 1) of K6a expression in humankeratinocyte cells plotted against rapamycin concentrations. FIG. 3bPanel 1 shows a timecourse analysis of effect of rapamycin on the humankeratinocyte. FIG. 3b Panel 2 shows quantitated values (from Panel 1) ofthe K6a expression in human kerotinocyte cells treated with rapamycinovertime.

FIGS. 4A-4D show treatment with rapamycin results in clinicalimprovement in three pachyonychia congenita patients. FIG. 4A shows painmeasures, based on arbitrary pain levels on a 1-10 scale (10 mostpainful), reported as either the morning level (upon waking—thereforenot as heavily influenced by daily activity (dots) or the runningaverage of morning pain levels reported (18 datapoints averaged, line).FIG. 4B shows results from The Dermatology Life Quality Index (DLQI)questionnaire which was utilized to assess the impact of rapamycintreatment on daily activities. The Y-axis DLQI data is inverted to alloweasier visualization of increased quality of life. DLQI and troughlevels are correlated (insert). FIG. 4C shows photographicbefore-and-after images of plantar hyperkeratosis, blisters andneurovascular structures. FIG. 4D shows magnification of the heel regionof patient IPCRR #10 from FIG. 4C containing the neurovascularstructures. Specifically, it shows how the rapamycin treatment resultedin the reduction or resolution of these painful regions (see arrows).The reduced hyperkeratosis observed may be at least partially due to theability of the patient to trim calluses much deeper due to recedingneurovascular structures and the associated decreased pain.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENT(S)

Reference will now be made to the exemplary embodiments illustrated, andspecific language will be used herein to describe the same. It willnevertheless be understood that no limitation of the scope of theinvention is thereby intended.

As used herein, “subject” refers to a mammal having a keratinhyperproliferation disorder. In some aspects, such subject may be ahuman.

The term “keratin hyperproliferation disorders” refers to skin disordersin which the inducible keratins, K6a, K6b, K16, and K17, areoverexpressed or inappropriately expressed. Non-limiting examples ofsuch disorders include keratosis pilaris (including follicularhyperkeratosis), pachyonychia congenita, hyperhidrosis, warts, andcalluses. Another example of such a skin disorder is psoriasis.

The term “mTOR inhibitor” refers to agents or compounds which areeffective in inhibiting mTOR or an inhibitor of the mTOR signalingpathway. mTOR is a serine/threonine kinase that regulates translationand cell division. Examples of mTOR inhibitors include but are notlimited to rapamycin (sirolimus) and its analogues and derivatives,temsirolimus, everolimus, the rapamycin prodrug AP-23573, AP-23481, thelike, and combinations thereof.

As used herein, the term “inhibition of” or “silencing of” with respectto genetic expression refers to the absence of, or at least anobservable decrease in, the level of protein (or protein activity) froma target gene.

As used herein, “effective amount” or “therapeutically effective amount”of a inhibitory agent refers to a sufficient amount of inhibitory agentto perform an intended task and achieve an intended result. For example,an effective amount of rapamycin may be an amount which is sufficient tosilence expression a keratin gene. It is understood that variousbiological factors may affect the ability of a particular agent toperform its intended task. Therefore, an “effective amount” or a“therapeutically effective amount” may be dependent in some instances onsuch biological factors. Further, while the achievement of therapeuticeffects may be measured by a physician or other qualified medicalpersonnel using evaluations known in the art, it is recognized thatindividual variation and response to treatments may make the achievementof therapeutic effects a somewhat subjective decision. The determinationof an effective amount is well within the ordinary skill in the art ofpharmaceutical sciences and medicine.

As used herein, sequences, compounds, formulations, delivery mechanisms,or other items may be presented in a common list for convenience.However, these lists should be construed as though each member of thelist is individually identified as a separate and unique member. Thus,no individual member of such list should be construed as a de factoequivalent of any other member of the same list solely based on theirpresentation in a common group without indications to the contrary.

Concentrations, amounts, and other numerical data may be expressed orpresented herein in a range format. It is to be understood that such arange format is used merely for convenience and brevity and thus shouldbe interpreted flexibly to include not only the numerical valuesexplicitly recited as the limits of the range, but also to include allthe individual numerical values or sub-ranges encompassed within thatrange as if each numerical value and sub-range is explicitly recited. Asan illustration, a numerical range of “about 0.5 to 10 g” should beinterpreted to include not only the explicitly recited values of about0.5 g to about 10.0 g, but also include individual values and sub-rangeswithin the indicated range. Thus, included in this numerical range areindividual values such as 2, 5, and 7, and sub-ranges such as from 2 to8, 4 to 6, etc. This same principle applies to ranges reciting only onenumerical value. Furthermore, such an interpretation should applyregardless of the breadth of the range or the characteristics beingdescribed.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood to one of ordinary skill inthe art to which this invention belongs. Although any methods, devicesand materials similar or equivalent to those described herein can beused in the practice or testing of the invention, representativemethods, devices, and materials are described below.

It has been discovered that the expression of the inducible keratinscontaining a translation regulatory motif (e.g. K6a and K17 and likelyK6b and K16) can be selectively inhibited by mTOR inhibitors.Inappropriate expression of these keratins appears to be involved in anumber of hyproliferation skin disorders including but not limited topsoriasis, keratosis pilaris, pachyonychia congenita, hyperhidrosis,warts, and calluses. It is believed that the mTOR inhibitors areeffective against these inducible keratins because the mRNAs encodingthese keratins contain within their 5′ untranslated regions translationregulatory sequences that usually begin with a “c” residue, followed bya track of pyrimidines (“c” or “u” residues) ranging from 4-14nucleotides. Messenger RNAs having this type of initiation sequence arereferred to as terminal oligopyrimidine (or TOP) mRNAs.

In one embodiment of the present invention, a method of treating orpreventing keratin hyperproliferation disorder is proposed. The methodincludes administering an amount of mTOR inhibitor to a subjectsuffering with a keratin hyperproliferation disorder. The mTORinhibitors which can be used in the present invention include but arenot limited to rapamycin (sirolimus) and its analogues and derivatives,temsirolimus, everolimus, the rapamycin prodrug AP-23573, AP-23481, andcombinations thereof. In one embodiment the mTOR inhibitor is rapamycin.In another embodiment mTOR inhibitor is a combination of rapamycin and asecond mTOR inhibitor.

The mTOR inhibitor can be administered in any method or mode known inthe art, including oral, topical, injection, and transdermaladministration. In one embodiment the mTOR inhibitor is administeredtransdermally. In another embodiment the mTOR inhibitor is administeredorally. When the mTOR inhibitor is administered orally, it can beadministered in an amount of from 2 mg/day to 20 mg/day. In oneembodiment, the oral administration can be formulated to be delivered ina single oral dosage form. In another embodiment, the mTOR inhibitor canbe administered via injection or intravenously. Administration byinjection can be done at or near an area in which the keratinhyperproliferation is manifested. In another embodiment the mTORinhibitor can be administered topically. In some situations it may bedesirable to administer the mTOR both orally and either topically ortransdermally. For example, in one embodiment, the mTOR inhibitor can beadministered orally and transdermally. When the mTOR inhibitor isadministered orally and by another method, the mTOR inhibitoradministered orally can be the same or different than the mTOR inhibitoradministered by the other method.

The treatment of a subject experiencing a keratin hyperproliferationdisorder using an mTOR can reduce or eliminate symptoms and/or signsassociated with the keratin disorder. In one embodiment, the treatmentusing the mTOR inhibitor can provide a reduction of a pain scores asmeasured by the Dermatology Life Quality Index (DLQI) (see Example 4) orother appropriate evaluation known in the art.

Example 1—mTOR Signaling in Mammals

Regulation of inducible keratin gene expression is believed to occurpost-transcriptionally, likely at the level of mRNA translation.Functional K6 and K16 mRNAs are found throughout normal epidermis butare not translated into protein. As most translational regulation ismediated through 5′ untranslated motifs (the inducible keratins may beregulated in a coordinate fashion), we performed a sequence comparisonusing published keratin mRNA sequences as well as genomic sequences. Thetranscriptional start site for human K6a was mapped by primer extensionto a “C” residue, which is imbedded in a tract of 21 pyrimidines. Theputative resulting transcript had seven pyrimidines at the 5′ end.Terminal oligopyrimidine (TOP) regulatory motifs (4-14 pyrimidinesadjacent to 5′ cap site, are known to be responsible for regulation of aclass of mRNAs (TOP mRNAs) at the level of mRNA translation in agrowth-dependent fashion. Treatment with the macrolide rapamycin(sirulimus) was shown to specifically down-regulate TOP mRNAtranslation. Rapamycin binds to and inhibits mTOR (mammalian target ofrapamycin), resulting in inactivation of p70 S6 kinase (p70^(S6K)) andactivation of eIF-4E binding protein 1 (4EBP1), leading to decreasedtranslation of TOP mRNAs. FIG. 1 shows the mTOR signaling pathway inmammals.

Example 2—Comparison of Untranslated Regions of Keratins K6a, K6b, K16,and K17

A comparison of the 5′ untranslated regions of the inducible keratins(K6a, K6b, K16, and K17) publicly available in the NCBI GenBank database(www.ncbi.nlm.nih.gov/Genbank) identified human and murine K6a as wellas human K17 as TOP mRNAs, each initiating with a “c” residue andcontaining the consensus oligopyrimidine tract at the 5′ terminus (seeFIG. 2). It is likely that the other inducible keratins also containthis element as their expression may be regulated in a coordinatefashion. The lack of a TOP element for human K6b and K16 likely reflectsthat the 5′ untranslated regions of mRNAs are often not mappedaccurately. As an example, immediately upstream of the reported 5′terminus of K6b exists an oligopyrimidine track, within which is likelythe initiation site of the mRNA (see FIG. 2). Furthermore, there is apyrimidine motif consisting of 14 continuous “u” and “c” residues in themiddle of the 5′ UTR of human K16, within which transcription may occur.

Example 3—Rapamycin Treatment of Human Keratinocytes

In order to test the hypothesis that inducible keratins are members ofthe TOP mRNA family, human HaCaT keratinocytes were treated withrapamycin. In one portion of the experiment, HaCaT cells were treatedwith increasing concentrations of rapamycin and harvested at 96 h andthe effect on K6 expression was monitored by western blot analysis.(FIG. 3A, Panel 1). Rapamycin effectively inhibited expression of the K6keratin, with little or not effect on a control (Lamin A/C). As shown inFIG. 3A Panel 2, K6a expression was indeed inhibited in a dose dependentfashion at low rapamycin concentrations (IC50 of ˜1 nM).

A timecourse analysis of effect of rapamycin on the HaCaT keratinocyteswas also performed. The HaCaT keratinocytes were treated with 10 nMrapamycin and harvested over a range of time points. At the indicatedtimes, cells were harvested and lysed in SDS-PAGE loading buffer,subjected to denaturing SDS-PAGE analysis and electroblotted tonitrocellulose. (FIG. 3B, Panel 1). K5, K6, and K14 expression weredetected by specific antibodies and visualized by the NBT/BCIP system.The timecourse analysis revealed that inhibition begins at about 36 hpost-treatment and persists for at least 144 h (see FIG. 3B, panel 2).

Example 4—Clinical Testing of Rapamycin in Subjects with PachyonychiaCongenita

A small number (n=3) of pachyonychia congenita patients, one female(IPCRR #10) with the K6a(N171K) mutation and two male PC patients (IPCRR#2 and #11) with the K16(N125D) mutation were identified through theInternational Pachyonychia Congenita Research Registry(www.pachyonychia.org). These patients were invited to participate in athree to five month off-label use of oral rapamycin (Rapamune®, WyethPharmaceuticals, Inc.). Rapamycin was given in the standard fashionfollowing typical recommendations for use as an adjunct therapy in renaltransplantation. Prior to initiation of therapy a pregnancy test wasperformed in the female patient (she was on oral contraceptiveprophylaxis) and all three patients received a pre-therapy evaluationincluding: cbc, CMP (sodium, potassium, chloride, carbon dioxide, aniongap, BUN, creatinine, glucose, ALT, AST, calcium, total protein,albumin, bilirubin), lipid panel (cholesterol, triglycerides, HDL, LDL,VLDL), UA with microanalysis, PA and lateral chest x-ray. The startingdose was 2 mg per day and trough levels were obtained at steady stateafter 2 weeks. The dosage was increased every two weeks until troughlevels reached a range of 9-12 ng/mL. Patients were re-evaluated foreffects and side effects every two weeks and photographs of plantarcalluses were taken to document their progress.

Laboratories were performed which included: rapamycin trough level, UAwith microanalysis, cbc with differential, CMP, lipid panel, pregnancytest (patient 10 only). Under the same WIRB protocol, patients alsocompleted a daily pain diary rating their level of pain on a scale of1-10 several times per day and a bi-weekly well-validated life qualityevaluation (DLQI) at the time of their clinic visit. The patient withthe K6a mutation collected callus shavings during her usual groomingroutine prior to, during, and after treatment with rapamycin. Theshavings were placed immediately in RNALater (Ambion) and RNA wasextracted for future quantitative real-time quantitative PCR (RT qPCR)analysis of keratin expression.

Patient reported pain (morning assessment) and DLQI quality of lifescores were plotted over time and with respect to dose of drug receivedand trough level over that time period. (see FIGS. 4A and 4B). PatientsIPCRR #10, 2, and 11 received rapamycin for 156, 109, and 56 days,respectively, with maximal trough levels of 10.4, 12.5, and 11.3 ng/mL,respectively, and with maximal doses of 8 mg/day, alternating 2 mg and 3mg on consecutive days, and 4 mg/day, respectively. All patientsexperienced a side effect that ultimately resulted in discontinuation ofuse of the drug. Patient 10 developed diarrhea and aphthous ulcers,patient 2 developed gastrointestinal distress with loss of appetite, andpatient 11 developed an acneiform follicular eruption. None of thepatients experienced any laboratory abnormalities or serious sideeffects. Significantly, in spite of these side effects arising fromsystemic administration of rapamycin, all three patients reported anincreased quality of life (as reflected by decreasing DLQI score, noteinverted axis in FIG. 4B) that paralleled the rapamycin trough level. Asmight be expected, the subjective pain scale was more variable than theDLQI scores, but as a general trend, the lower pain scores correspondedto higher trough levels. Of particular note for patient 10 is thediscontinuation of rapamycin (days 145-148 due to concerns regardingdiarrhea while traveling) during which time a trough level was notobtained. This period was associated with high level of pain followed bydecrease of pain level when drug treatment was re-initiated and assumedto reach therapeutic levels (trough level was not obtained). The simplepain scale used in this study was not as good as the DLQI in adequatelycapturing the overall subjective experience of pain in these patients,especially patients 2 and 11. Both of these patients reported that theyfelt their pain was improved, but the pain scores did not reflect theirgeneral impression. These patients reported that this was due in part tothe increased level of activity that spontaneously occurs when paindecreases. An improved pain scale is currently under development, whichincorporates activity level into the subjective reporting system.

In addition to subjective improvement of plantar pain and improvedquality of life, patients also demonstrated important clinical changesin the plantar calluses. FIG. 4C shows photographs taken of the plantarkeratoderma before initiation of systemic rapamycin therapy and 12 weeksinto the treatment course. The photographs demonstrate decreasedkeratoderma following treatment, particularly in the K6a PC patient. Ofnote, this patient has long noted that the level to which she is able toremove callus is determined by the level at which the blade reachescapillaries and associated pain fibers. At the 12 week time point, thedepth at which these neurovascular structures were found appeared to beregressed relative to baseline (see FIG. 4D).

Example 5—Treatment of Keratin Hyperproliferation Using Temsirolimus

A subject suffering from a keratin hyperproliferation disorder isadministered a therapeutically effective oral dose of temsirolimus(TORISEL™) for a period of about 120 days. During the time of treatment,the subject's pain and keratoderma associated with the keratinhyperproliferation disorder are reduced.

While the forgoing examples are illustrative of the principles of thepresent invention in one or more particular applications, it will beapparent to those of ordinary skill in the art that numerousmodifications in form, usage and details of implementation can be madewithout the exercise of inventive faculty, and without departing fromthe principles and concepts of the invention. Accordingly, it is notintended that the invention be limited, except as by the claims setforth below.

What is claimed is:
 1. A method of treating pachyonychia congenita in asubject comprising: administering to the subject a therapeuticallyeffective amount of an mTOR inhibitor selected from the group consistingof rapamycin (sirolimus), a rapamycin derivative, a rapamycin prodrug,and combinations thereof.
 2. The method of claim 1, wherein therapamycin derivative is a member selected from the group consisting of:temsirolimus, everolimus, and combinations thereof.
 3. The method ofclaim 1, wherein the rapamycin prodrug is selected from the groupconsisting of AP-23573, AP-23481, and combinations thereof.
 4. Themethod of claim 1, wherein the mTOR inhibitor is rapamycin.
 5. Themethod of claim 1, wherein the mTOR inhibitor is a combination of two ormore mTOR inhibitors.
 6. The method of claim 1, wherein theadministration of said mTOR inhibitor is oral.
 7. The method of claim 6,wherein the mTOR inhibitor is administered in an amount of from 2 mg/dayto 20 mg/day.
 8. The method of claim 1, wherein the administration ofsaid mTOR inhibitor is topical.
 9. The method of claim 1, wherein theadministration of the mTOR inhibitor is transdermal.
 10. The method ofclaim 1, wherein the administration of the mTOR inhibitor isintravenous.
 11. The method of claim 1, wherein the administration ofthe mTOR inhibitor is both oral and topical.
 12. The method of claim 11,wherein the mTOR inhibitor administered orally is the same as the mTORinhibitor administered topically.
 13. The method of claim 11, whereinthe mTOR inhibitor administered orally is different from the mTORinhibitor administered topically.
 14. The method of claim 1, wherein theadministration of the mTOR inhibitor is both oral and transdermal. 15.The method of claim 14, wherein the mTOR inhibitor administered orallyis the same as the mTOR inhibitor administered transdermally.
 16. Themethod of claim 14, wherein the mTOR inhibitor administered orally isdifferent from the mTOR inhibitor administered transdermally.
 17. Themethod of claim 1, wherein pachyonychia congenita results fromoverexpression or inappropriate expression of a keratin encoded by amRNA having a terminal oligopyrimidine (TOP) motif.
 18. A method oftreating pachyonychia congenita in a subject comprising administering tothe subject a therapeutically effective amount of rapamycin.
 19. Themethod of claim 18, wherein the administration is systemic, topical,transdermal, or a combination thereof.